Brake Pedal Force Sensor Membranes for Off-Center Loading

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Solution Overview

Problem

Conventional force sensors face challenges in accurately measuring axial load forces, especially when they are off-center or off-axis, due to non-uniform strain field distribution and increased stress on silicon glass, leading to potential damage and reduced accuracy.

Innovation Solution

A brake pedal system with a force transfer member and dual membranes that offset sideloading, using micro-fused strain gauges to ensure consistent force detection, even with off-center loading, by maintaining a symmetrical strain field and reducing stress on the sensor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional force sensors are used to measure axial load forces, then the measurement can be obtained, but the accuracy deteriorates when forces are off-center or off-axis due to non-uniform strain field distribution

Engineering Contradiction:

Improveforce measurement accuracyVSAvoidsensor performance under off-center loading

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies asymmetry by intentionally designing the strain gauge arrangement to compensate for asymmetric loading conditions. The strain gauges are positioned and oriented in specific asymmetric patterns that counterbalance the effects of off-center forces, allowing the sensor to maintain measurement accuracy even when the applied force is not perfectly centered on the sensing element.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent changes the parameters of the strain gauge configuration, including their positions, orientations, and arrangement patterns on the sensing element. By optimizing these parameters, the sensor can accurately measure axial forces while compensating for the effects of off-center loading through careful parameter selection and adjustment.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If conventional force sensors measure off-center forces, then force detection is attempted, but the stress on silicon glass increases leading to potential damage

Engineering Contradiction:

Improveforce detection capabilityVSAvoidsilicon glass stress resistance

Core Design Contradiction:

Measurement precisionVSStrength

Solution Approach 1:

The patent applies local quality by strategically positioning strain gauges in specific locations on the sensing element where they can detect forces while minimizing stress concentration on the silicon glass. The sensing element is designed with varying local properties, placing measurement points in regions that can detect off-center forces without creating excessive stress on the glass structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements beforehand cushioning by designing the sensing element and strain gauge arrangement to preemptively handle off-center loading conditions. The structure is pre-configured to distribute and absorb the additional stresses caused by off-center forces before they can damage the silicon glass, protecting the sensor from potential damage.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If off-center loads are applied to conventional force sensors, then force measurement is attempted, but the strain field position shifts affecting accuracy

Engineering Contradiction:

Improveforce measurement under various loading conditionsVSAvoidstrain field position stability

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies universality by designing a sensing element and strain gauge arrangement that can accurately measure forces regardless of their position or direction. The multi-functional design allows the same sensor configuration to handle both centered and off-center loads, as well as forces applied at different angles, maintaining measurement precision across diverse loading conditions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system provides improved accuracy and durability in measuring forces applied to a brake pedal, enabling reliable vehicle control by minimizing sensor damage and maintaining consistent strain field symmetry.

Implementation Method 1

The same MSG technology can also be used to measure forces. For example, an applied force will result in a strain field change on the sensing element of the sensor. Using strain gauges, this strain field change can be measured and will be transformed into a ratio-metric output voltage.

Methodology Applied

Scientific EffectStrain gauge measurement: Piezoresistive Effect

Implementation Method 2

Methodology Applied

Scientific EffectForce offsetting: Mechanical Force

Data Source

PatentUS12467808B2Brake pedal with force sensor and membranes

Publication Date: 2025.11.11 SENSATA TECHNOLOGIES INC

AI summary

A pedal system includes a user interface, e.g., a pedal for contacting by a driver of a vehicle, a force sensor, and a force transfer member between the user interface and the force sensor. A force applied to the user interface is detected and measured by the force sensor. One or more membranes, e.g., two membranes, are arranged at an outer surface of the force transfer member to decouple off-center loading and non-uniform forces, e.g., resulting from off-center force application at the user interface.